I want to find all products on someone's favorite shops and found there is many nested code when coding in reactive way. Is this the correct way? Or if there are some better methods?
#Component
public class ProductController {
#Autowired
ShopRepo shopRepo;
#Autowired
ProductRepo productRepo;
public Mono<ServerResponse> products(ServerRequest req) {
String userid = req.queryParam("userid");
Flux<Shop> shops = shopRepo.favorite(uid);
return shops
.flapMap(s -> Mono.just(s.getId()))
.collectList()
.flapMap(list -> {
String[] shopIds = list.toArray(new String[list.size()]);
return ServerResponse.ok().body(productRepo.findByShops(shopIds), Product.class);
});
}
}
Related
I have two class like this :
public class Forecast {
private List<Element> elements;
private Person person;
}
public class Element {
private String element;
}
I have a constant of String[] like this :
private static final String[] ELE = {"element1", "element2", "element3"};
I would like to retrieve all the elements of my list in forecast which contains one of the elements of my constant with Stream.
So, I started by doing this to test :
public List<Element> getElement(String person) {
return getElement(person).getList()
.stream()
.filter(r -> r.get(0).getElement.equals("element1"))
.collect(Collectors.toList());
}
Now I would like to use my constant ELE, and I don't find how to go through it and test my elements
Thanks
private static final List<String> ELE_LIST = java.util.Arrays.asList(ELE);
public List<Element> getElement(String person) {
return getElement(person).getList()
.stream()
.filter(r -> ELE_LIST.contains(r.get(0).getElement()))
.collect(Collectors.toList());
}
I am trying to learn the repository pattern and looking at a generic repository I cannot see how to handle customized select statements. For example, using this article the author uses a select by ID and a select all.
public interface IGenericRepository<T> where T:class
{
IEnumerable<T> SelectAll();
T SelectByID(object id);
void Insert(T obj);
void Update(T obj);
void Delete(object id);
void Save();
}
Later the article the IGenericRepository interface is implemented using Northwind. Then that is used to create a Customer controller.
public class CustomerController : Controller
{
private IGenericRepository<Customer> repository = null;
public CustomerController()
{
this.repository = new GenericRepository<Customer>();
}
...
This would handle selecting a list of all Customers or for one Customer by ID but where I get stuck is some more real world examples like "select all Customers for a client" or "select all Customers for a region". Plus, you could have another controller based on a different entity that would filter on different attributes. I assume I'm missing something basic. If the user interface needed to present the Customer entity (or any other entity) by various filters, how would this be done by sticking with one generic repository?
Here you go; to handle any select criteria apart from the Id, you can add Where method
like below
public interface IGenericRepository<T> where T:class
{
IEnumerable<T> SelectAll();
T SelectByID(object id);
IEnumerable<T> Where(Expression<Func<T,bool>> predicate)// this one
void Insert(T obj);
void Update(T obj);
void Delete(object id);
void Save();
}
Now in the Where method implementation do it like this
public IEnumerable<T> Where(Expression<Func<T,bool>> predicate)
{
return _objectSet.Where(predicate).AsEnumerable();
}
Here _objectSet in created in repository constructor like this :
public Repository(ObjectContext context)
{
_context = context;
_objectSet = _context.CreateObjectSet<T>();
}
public CustomerController()
{
_context = new NorthwindEntities();
_reporsitory = new Repository<Customer>(_context);
}
Use of Where method like
reporsitory.Where(c=>c.Country=="Canada").ToList();
For full reference see this project on codeplex (download /browse source code)
https://efgenericrepository.codeplex.com/SourceControl/latest
I think the implementation of the GenericRepository should somehow be able to return the IQueryable of current entity, like adding Get() method.
protected IQueryable<T> Get() // Notice that the access modifier is protected.
{
return table;
}
Then you could just create a derived class from GenericRepository and add a select method that accepts the Filter class.
public class CustomerRepository : GenericRepository<Customer>
{
public IEnumerable<T> SelectAll(CustomerFilter filter){ .. }
}
The filter class contains 2 filters.
public class CustomerFilter
{
public int? ClientId { get; set; }
public int? RegionId { get; set; }
}
Then the SelectAll implementation would be.
public IEnumerable<T> SelectAll(CustomerFilter filter)
{
var query = Get();
if (filter == null)
{
return query;
}
if (filter.ClientId.HasValue)
{
query = query.Where(q => q.ClientId == filter.ClientId.Value);
}
if (filter.RegionId.HasValue)
{
query = query.Where(q => q.RegionId == filter.RegionId.Value);
}
return query;
}
In the controller, calling it like.
public ActionResult Get(int? clientId, int? regionId)
{
var filter = new CustomerFilter { ClientId = clientId, RegionId = regionId };
var customers = _repository.SelectAll(filter);
return View();
}
You might need to see this post as your reference.
An approach I've seen in one asp.net mvc based mission critical app, is to use the generic interface as defined in the question. Then there is an abstract class that implements that interface. And there is one more repository class that inherits the abstract class, which has all methods specific to that class.
public interface IGenericRepository<T> where T:class
{
...
}
public abstract class GenericRepository<T> : IGenericRepository where T:class
{
...
}
And the CustomerRepository class
public class CustomerRepository : GenericRepository<Customer>
{
//add method specific to Customer like select Customers in specific country
}
And in the controller
public class CustomerController : Controller
{
private CustomerRepository repository = null;
public CustomerController()
{
this.repository = new CustomerRepository();
}
...
I am currently trying to implement my own version of the polymorphic types demo that is located here:
https://github.com/MvvmCross/MvvmCross-Tutorials/tree/master/Working%20With%20Collections
And I have it working as the demo shows. However, I am looking to extend that demo to have more complex controls inside of the MvxListView. I am wanting to have each of the list items control a fragment that has a View and a core ViewModel for additional processing.
I am unsure of the correct way of implementing this.
The code that I am using to create the custom view is this:
protected override View GetBindableView(View convertView, Object source, Int32 templateId)
{
var listItem = (TodayPanel) source;
if (listItem != null)
templateId = (Int32) typeof (Resource.Layout).GetField(listItem.View).GetValue(null);
return base.GetBindableView(convertView, source, templateId);
}
As always, it's probably something simple that I am missing, but any help would be appreciated.
Thanks!
I hate it when this happens, but after posting my question, I stepped away from the computer for a little bit and started to do something else. At that point, everything clicked into place. Stuart, in response to your question, the TodayPanel was NOT an MvxModelView, and therein was the crux of the problem. What I was doing was passing a list of TodayPanels into the listview, which was an SQLite entity object and not an MvxModelView object.
For others that might be struggling with this, I am going to post my solution here.
So here is what I ended up doing. I first created a class for each of the TodayPanel entity objects that inherited from an abstract base class that inherited from MvxModelView.
public abstract class TodayBaseViewModel : MvxViewModel
{
protected TodayViewModel TodayViewModel { get; set; }
protected IDataService DataService { get; set; }
public String Name { get; set; }
public String Title { get; set; }
public Boolean CanHide { get; set; }
public Boolean Visible { get; set; }
public Int32 SortOrder { get; set; }
public String View { get; set; }
protected abstract void SetEventHandlers();
protected BaseViewModel(IDataService dataService)
{
DataService = dataService;
}
public void Init(TodayViewModel todayViewModel)
{
TodayViewModel = todayViewModel;
SetEventHandlers();
}
}
I made it abstract as I wanted 0 or more event handlers to be attached in the final class. which is done through the abstract SetEventHandlers() method:
public class CoachSaysViewModel : TodayBaseViewModel
{
public CoachSaysViewModel(IDataService dataService)
: base(dataService)
{
}
protected override void SetEventHandlers()
{
TodayViewModel.ConnectionUpdated += TodayViewModelConnectionUpdated;
TodayViewModel.NewActivityReceived += TodayViewModelNewActivityReceived;
}
protected void TodayViewModelNewActivityReceived(Object sender, EventArgs.ActivityReceivedEventArgs e)
{
}
protected void TodayViewModelConnectionUpdated(Object sender, EventArgs.ConnectionUpdatedEventArgs e)
{
}
}
Then I created an extension method that converts the TodayPanel entity to one of the classes that inherits from TodayBaseViewModel.
public static BaseViewModel ToBaseViewModel(this TodayPanel todayPanel, TodayViewModel todayViewModel)
{
BaseViewModel model = null;
switch (todayPanel.View)
{
case "Today_QuickView":
model = Mvx.IocConstruct<QuickViewViewModel>();
break;
case "Today_CoachSays":
model = Mvx.IocConstruct<CoachSaysViewModel>();
break;
}
if (model == null)
return null;
model.CanHide = todayPanel.CanHide;
model.Name = todayPanel.Name;
model.SortOrder = todayPanel.SortOrder;
model.Title = todayPanel.Title;
model.View = todayPanel.View;
model.Visible = todayPanel.Visible;
model.Init(todayViewModel);
return model;
}
That then allowed me to create a list of MvxViewModels that are then bound to the MvxListView and hence are allowed to do the additional processing that I am wanting to do.
I'm sure that there are some improvements that I can do to the end result, and if you see anything feel free to point it out. :)
I have successfully setup a simple mvc application that lists teams. I'm using Ninject to inject the appropriate repository depending on the controller (thanks to stack overflow ;). All looks good, except that the repository code looks exactly the same. And I know that's wrong. So my TeamRepository has two classes (for now).
public class SwimTeamRepository : ITeamRepository<SwimTeam>
{
private readonly Table<SwimTeam> _teamTable;
public SwimTeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<SwimTeam>());
}
public IQueryable<SwimTeam> Team
{
get { return _teamTable; }
}
}
public class SoccerTeamRepository : ITeamRepository<SoccerTeam>
{
private readonly Table<SoccerTeam> _teamTable;
public SoccerTeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<SoccerTeam>());
}
public IQueryable<SoccerTeam> Team
{
get { return _teamTable; }
}
}
They look exactly the same except for the Class and Table name, so clearly I need to re-factor this. What would be the best approach here? Singleton? Factory Method?
Thanks in advance!
You could use generics:
public interface ITeamRepository<T>
{
}
public class TeamRepository<TTeam> : ITeamRepository<TTeam>
where TTeam : Team
{
private readonly Table<TTeam> _teamTable;
public TeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<TTeam>());
}
public IQueryable<TTeam> Team
{
get { return _teamTable; }
}
}
public class Team
{
}
public class SwimTeam : Team
{
}
Then use it like so...
public void MyMethod()
{
var repository = new TeamRepository<SwimTeam>();
}
...and set up your IoC container w/ Ninject like so...
public class MyModule : NinjectModule
{
public override void Load()
{
Bind<ITeamRepository<SwimTeam>>
.To<TeamRepository<SwimTeam>>();
}
}
public void MyMethod()
{
var repository = kernel.Get<ITeamRepository<SwimTeam>>();
}
If you want to get REAL generic and have a single repository for ALL of your mapped classes, you can do something like this:
public interface IRepository
{
IQueryable<T> Get<T>() where T : class, new();
}
public class Repository : IRepository, IDisposable
{
private DataContext _dataContext;
public Repository(string connectionString)
{
_dataContext = new DataContext(connectionString);
}
public IQueryable<T> Get<T>()
where T : class, new()
{
return _dataContext.GetTable<T>().AsQueryable();
}
public void Dispose()
{
if (_dataContext != null)
{
_dataContext.Dispose();
_dataContext = null;
}
}
}
...which you could call like so (after setting up your Ninject container)...
using (var repository = kernel.Get<IRepository>())
{
var swimTeam = repository.Get<SwimTeam>();
}
Since Ninject takes care of the life-cycle management of your objects, you don't HAVE to wrap the repository in a using statement. In fact, you don't want to use a using statement there at all if you plan to use the repository more than once within the scope of its lifetime. Ninject will automatically dispose of it when it's life-cycle ends.
Here's a good article by Rob Conery on using this kind of technique to reduce the friction of using different ORMs.
EDIT by keeg:
I Think
public class TeamRepository<TTeam> : ITeamRepository<TTeam> where TTeam : Team {}
Should be
public class TeamRepository<TTeam> : ITeamRepository<TTeam> where TTeam : class {}
Please correct if I'm wrong.
Is this what you want?
public class TeamRepository : ITeamRepository<T>
{
private readonly Table<T> _teamTable;
public TeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<T>());
}
public IQueryable<T> Team
{
get { return _teamTable; }
}
}
I've tried to build some base project with above technologies. I wanted maximum flexibility and testability so I tried to use patterns along the way to make this as a base for future projects. However, it seem
something is wrong or whatever and I really need help here. So i have two questions :
Is there anything wrong with my current code? I've applied patterns correctly? Any suggestions or recommendation that would lead me in the right direction?
Why do this code actually connect to the database, create it, but doesn't support insert even if I perform the corrects operation? (Look at the end of the post for details about this error) FIXED
I believe this could also help others since I haven't found enough information in order to make something up correctly. I am pretty sure lots of people try to do it the right way and are not sure like me if what I am doing is right.
I have two entities: Comment and Review
COMMENT
public class Comment
{
[Key]
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual string Author { get; set; }
public virtual string Body { get; set; }
}
REVIEW
public class Review
{
[Key]
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual string Author { get; set; }
public virtual string Body { get; set; }
public virtual bool Visible { get; set; }
public IEnumerable<Comment> Comments { get; set; }
}
I built up a base repository for each of them this way :
GENERIC REPOSITORY
public abstract class EFRepositoryBase<T> : IRepository<T> where T : class
{
private Database _database;
private readonly IDbSet<T> _dbset;
protected IDatabaseFactory DatabaseFactory { get; private set; }
protected Database Database { get { return _database ?? (_database = DatabaseFactory.Get()); } }
public EFRepositoryBase(IDatabaseFactory databaseFactory)
{
DatabaseFactory = databaseFactory;
_dbset = Database.Set<T>();
}
public virtual void Add(T entity)
{
_dbset.Add(entity);
}
public virtual void Delete(T entity)
{
_dbset.Remove(entity);
}
public virtual T GetById(long id)
{
return _dbset.Find(id);
}
public virtual IEnumerable<T> All()
{
return _dbset.ToList();
}
}
For specific operations, I use an interface:
public interface IReviewRepository : IRepository<Review> {
// Add specific review operations
IEnumerable<Review> FindByAuthor(string author);
}
So I am getting the generics operations from the abstract class plus the specific operations:
public class EFReviewRepository : EFRepositoryBase<Review>, IReviewRepository
{
public EFReviewRepository(IDatabaseFactory databaseFactory)
: base(databaseFactory)
{ }
public IEnumerable<Review> FindByAuthor(string author)
{
return base.Database.Reviews.Where(r => r.Author.StartsWith(author))
.AsEnumerable<Review>();
}
}
As you figured out, I also use a database factory will produce the database context :
DATABASE FACTORY
public class DatabaseFactory : Disposable, IDatabaseFactory
{
private Database _database;
public Database Get()
{
return _database ?? (_database = new Database(#"AppDb"));
}
protected override void DisposeCore()
{
if (_database != null)
_database.Dispose();
}
}
DISPOSABLE (Some extensions methods...)
public class Disposable : IDisposable
{
private bool isDisposed;
~Disposable()
{
Dispose(false);
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
private void Dispose(bool disposing)
{
if (!isDisposed && disposing)
{
DisposeCore();
}
isDisposed = true;
}
protected virtual void DisposeCore()
{
}
}
DATABASE
public class Database : DbContext
{
private IDbSet<Review> _reviews;
public IDbSet<Review> Reviews
{
get { return _reviews ?? (_reviews = DbSet<Review>()); }
}
public virtual IDbSet<T> DbSet<T>() where T : class
{
return Set<T>();
}
public Database(string connectionString)
: base(connectionString)
{
//_reviews = Reviews;
}
public virtual void Commit()
{
base.SaveChanges();
}
/*
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
// TODO: Use Fluent API Here
}
*/
}
And to finish, I have my unit of work....
UNIT OF WORK
public class UnitOfWork : IUnitOfWork
{
private readonly IDatabaseFactory _databaseFactory;
private Database _database;
public UnitOfWork(IDatabaseFactory databaseFactory)
{
_databaseFactory = databaseFactory;
}
protected Database Database
{
get { return _database ?? (_database = _databaseFactory.Get()); }
}
public void Commit()
{
Database.Commit();
}
}
I also bound using Ninject the interfaces:
NINJECT CONTROLLER FACTORY
public class NinjectControllerFactory : DefaultControllerFactory
{
// A Ninject "Kernel" is the thing that can supply object instances
private IKernel kernel = new StandardKernel(new ReviewsDemoServices());
// ASP.NET MVC calls this to get the controller for each request
protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
{
if (controllerType == null)
return null;
return (IController)kernel.Get(controllerType);
}
private class ReviewsDemoServices : NinjectModule
{
public override void Load()
{
// Bindings...
Bind<IReviewRepository>().To<EFReviewRepository>();
Bind<IUnitOfWork>().To<UnitOfWork>();
Bind<IDatabaseFactory>().To<DatabaseFactory>();
Bind<IDisposable>().To<Disposable>();
}
}
}
However, when I call in the constructor (the default action) ...
public class ReviewController : Controller
{
private readonly IReviewRepository _reviewRepository;
private readonly IUnitOfWork _unitOfWork;
public ReviewController(IReviewRepository postRepository, IUnitOfWork unitOfWork)
{
_reviewRepository = postRepository;
_unitOfWork = unitOfWork;
}
public ActionResult Index()
{
Review r = new Review { Id = 1, Name = "Test", Visible = true, Author = "a", Body = "b" };
_reviewRepository.Add(r);
_unitOfWork.Commit();
return View(_reviewRepository.All());
}
}
This seem to create the database but doesnt't insert anything in the database in EF4. It seem that I may figured out the problem.. while looking at the database object.. the connection state is closed and server version throw an exception of this kind :
ServerVersion = '(((System.Data.Entity.DbContext (_database)).Database.Connection).ServerVersion' threw an exception of type 'System.InvalidOperationException'
I am doing the right things? Is there anything wrong in what I've built ?
Also if you have recommandation about the code I posted, I would be glad. I am just trying to the learn the right way for building any kind of application in MVC 3. I want a good a start.
I use :
Entity Framework 4 with Code-First
ASP.NET MVC 3
Ninject as DI Container
SQL Server Express (not R2)
Visual Studio 2010 Web Express
Eww. This one was sneaky. Actually i don't know ninject much so i couldnt figure it out right away.
I found the solution for the SECOND question which was related to the error by finding that ninject actually shoot two instance of the DatabaseFactory, one for the repository and one for the unit of work. Actually, the error was not the problem. It was an internal error in the object database but its normal i think since im using Entity Framework.
The real problem was that Ninject was binding two different instance of IDatabaseFactory which lead to 2 connection open.
The review was added to the first set in _reviewRepostory which was using the first instance of the Database.
When calling commit on the unit of work.. it saved nothing due to the fact that the review wasnt on this database instance. In fact, the unit of work called the databasefactory which lead to creating a new instance since ninject sent a new instance of it.
To fix it simply use :
Bind<IDatabaseFactory>().To<DatabaseFactory>().InSingletonScope();
instead of
Bind<IDatabaseFactory>().To<DatabaseFactory>();
And now all the system work correctly!
Now, would love some answers regarding the first question which was if there anything wrong with my current code ? Ive applied patterns correctly ? Any suggestions or recommendation that would lead me in the right direction ?
One small observation: by having your EFRepositoryBase and IReviewRepository have methods that return an IEnumerable<> instead of an IQueryable<>, you prevent subsequent methods from adding filter expressions/constraints or projections or so on to the query. Instead, by using IEnumerable<>, you will do any subsequent filtering (e.g. using LINQ extension methods) on the full result set, rather than allowing those operations to affect and simplify the SQL statement that gets run against the datastore.
In other words, you are doing further filtering at the webserver level, not at the database level where it really belongs if possible.
Then again, this may be intentional - sometimes using IEnumerable<> is valid if you do want to prevent callers of your function from modifying the SQL that is generated, etc.